PARIS - France is the home of “Liberté, Égalité et Fraternité” and the birthplace of the Rights of Man. But running simultaneously through the country’s political traditions is a much darker strain of racism and antisemitism, according to the New York Times.

It looks as if a new, more virulent chapter in that history of French bigotry may now be opening — with a seemingly unlikely champion. Éric Zemmour, a far-right polemicist who officially declared on Tuesday that he is running in next April’s presidential election, is the loudest and most extreme voice of French racism today.

The great irony is that Mr. Zemmour, twice convicted of inciting racial hatred and discrimination, is a Jew — a member of the very community once targeted by the racists whose traditions he inherits and invokes. He has updated France’s oldest hatred for a new era.

The roots of the current French far right can be understood only in the context of its prehistory. Religious antisemitism was long a staple of reactionary thought in France. With the advent of mass immigration from France’s former colonies, antisemitism was largely replaced by anti-Black and, especially, anti-Arab racism.

Since the 1970s, the political voice of this racism has been the far-right National Front party, now rebranded as the National Rally as part of an attempt to enter the mainstream. This party has twice reached the second round of the presidential elections, in 2002 and 2017. Mr. Zemmour is now outflanking it from the right.

It doesn’t take much to see the roots of Mr. Zemmour’s ideology: his insistence that France is engaged in a religious war with Islam and a race war with its Black and Arab population; that entire neighborhoods of its major cities have been “colonized” by Muslims; that Islam is a religion of terror; that French Muslims must be made to choose between Islam and France (which he considers mutually exclusive).

All of it is an updating of the Jew-hatred of a century and a quarter ago. In the same way that the antisemites of the past accused the omnipotent, maleficent Jews of being guilty of crimes of all kinds, even of causing the flooding of the Seine, for Mr. Zemmour there is no crime for which Muslims are not guilty.